Forecasters said up to 40cm (16in) of snow could fall in some areas as the worst of the cold snap switches from the north to the south.

Heavy snow forced the closure of schools, roads and airports around the country. Police warned of hazardous driving conditions and the Met Office predicted worse could follow overnight and on Wednesday.

The Met Office said Dorset, Hampshire, Oxfordshire, Berkshire and Wiltshire could see "exceptionally heavy snowfall". Between 15cm and 30cm (6in and 12in) of snow is expected but there could be "in excess of 40cm (16in)".

"This is expected to cause widespread disruption to the transport network and could lead to problems with power supplies," the Met Office said.

A spokeswoman said warnings of either heavy snow or ice were in place for every county in the UK. Parts of Surrey, Hampshire, West Sussex, East Sussex, Buckinghamshire and the Isle of Wight are also expected to see "extreme" conditions.

National Grid, which issued only its second ever gas balancing alert (GBA) on Monday after a 30% surge in seasonal demand, said the warning would not be repeated on Wednesday. GBAs are a way of warning customers on "interruptible contracts" to ease off on the fuel as well as encouraging suppliers to bring in more gas. A spokeswoman said the situation was being monitored on a daily basis but stressed supplies were in place to cope with demand.

There were widespread travel problems with Manchester Airport and the John Lennon Airport in Liverpool being forced to temporarily close. Passengers at Heathrow, Gatwick, Glasgow and Leeds Bradford International also faced delayed flights. Channel Tunnel services, badly disrupted before Christmas due to problems with Eurostar trains, were held up after a problem with a Eurotunnel freight shuttle train.

On the roads, heavy snow caused a section of the A66 to be shut in both directions in Cumbria and a succession of accidents added to drivers' difficulties on many routes. Meanwhile, supermarkets saw a surge in panic buying as shoppers stocked up on essential items.

In Berkshire, a six-year-old boy was fighting for life in hospital after falling through ice in a garden pond while playing with a friend. It is thought the boy had been underwater for half an hour before he was pulled out by firefighters. His playmate, thought to be another boy around the same age, raised the alarm after the accident in Crookham Common, near Thatcham

NOTE- FEEL SO LUCKY HAVE SAFE JOURNEY LAST WEEK TO SCOTLAND@ SNOWLAND ALTHOUGH THE WEATHER ALMOST NOT PROMISING IN THAT TIME.....BUT GOT BAD EXPERIENCES JOURNEY WHEN BACK FROM DUBLIN LAST 20 DEC 2009.....THANKS TO ALMIGHTY GIVE ME CHANCES TO SEE THE SNOW BEAUTIES OF THE SCENERY AS MY MIND THERAPY..WALLAHAUALAM....